1. Field of the Invention.
The invention relates to a cylinder head of an internal combustion engine, with a coolant space associated with each combustion chamber of the cylinderhead and with at least one coolant inlet and at least one coolant outlet.
2. Description of Related Art.
A coolant arrangement for a multi-cylinder internal combustion engine is disclosed in German DE 195 42 492 C1. In this coolant arrangement, a coolant space includes a plurality of coolant space areas provided for a combustion chamber of the engine. The coolant space is defined between the base of the cylinder head, the outer walls, and the top of the cylinder head. The coolant space areas are supplied with coolant through inlets in communication with the coolant jacket of the engine block. The individual coolant space sections are flow connected in series with the coolant jacket of the cylinders and thus cannot be individually subjected to different flow patterns or be supplied with coolant differently.
The object of the invention is to provide a coolant housing with individual coolant spaces in a manner so that each individual coolant space or section can be subjected to a different flow or can be supplied separately with coolant to a different degree. Thus, coolant can be supplied separately to critical regions for individual cylinders.
The object is achieved by including providing in the cylinderhead at least a first coolant chamber and at least a second coolant chamber, which are separate from one another. The coolant outlet of the second coolant chamber is in communication with the first coolant chamber. This permits directing coolant flow inside the coolant spaces in an optimized manner to specifically cool critical (hot) regions, such as the center of the combustion chamber and the area adjacent the exhaust valve(s).
It is furthermore possible to arrange the coolant inlet of the second coolant chamber exterior to the coolant housing and to provide for a coolant outlet of the second coolant chamber in the coolant space of the cylinderhead.
Furthermore, it has been found that it is desirable that the coolant outlet of the second coolant chamber be designed as a coolant flow passage arranged near an exhaust valve. The design of the coolant outlet as a transverse flow passage subjects the critical (hot) region near the exhaust valve and the combustion chamber to coolant flow providing for specific cooling in these critical regions.
To this end, it is also advantageous that the coolant inlet and outlet of the first coolant chamber of the coolant housing are positioned exteriorly to the coolant housing. The two coolant chambers or the coolant space can therefore be subjected to different flow patterns in different areas of the cylinderhead for cooling them in a specific manner.
Finally, in a preferred embodiment of the invention, provision is made for the coolant inlet to be in communication with both the first and the second coolant chamber. In this way, both coolant chambers are jointly supplied with coolant.
Therefore, the coolant chambers of the cylinder head are entirely separate from the coolant spaces of the engine block.
In the manufacture of the subject cylinderhead with coolant spaces, sand cores are configured in accordance with the shape of the coolant spaces. This design does not require additional bores or machining steps for the forming of the coolant spaces. Accordingly, a cylinderhead with cooling chambers as provided by this invention are substantially more cost-effective from a casting point of view.
Of particular importance for the present invention is the use of an external valve at the inlet of the first and second coolant chambers. By means of the valve, the coolant space can be supplied with separate or individualized flows in accordance with the desired cooling capacity.
In connection with the design and arrangement of the subject invention, it is of advantage if the top of the first coolant chamber is disposed approximately level with the top of the combustion chamber.
Furthermore, it is advantageous to locate the second coolant chamber near an outer end of the first coolant chamber and near the exhaust side of the cylinderhead. This permits additional coolant flow to be supplied near this critical hot exhaust side.
In addition, it is advantageous to provide flow conducting or flow directing elements for the coolant to ensure an optimized flow pattern inside the cooling chambers.
Furthermore, it is advantageous for the first and the second cooling chambers of a combustion chamber to have a common coolant inlet. Then, depending on the particular requirements of an internal combustion engine, individual coolant chambers may be supplied with individual coolant flows or with a combined flow. Also, the coolant outlet of the second coolant chamber should conduct coolant past the combustion chamber top portion and past the center of the combustion chamber.
For simplification, the coolant spaces of any two adjacent combustion chamber areas should have a common coolant inlet and a common coolant outlet.